mobile = [['apple', 'ios', '100', '10'], ['pear', 'android', '200', '20'], ['apple', 'ios', '500', '50'],
          ['pear', 'android', '600', '60']]
mobiledict = {}
for elem in mobile:
    key = (elem[0], elem[1])
    if key in mobiledict:
        mobiledict[key][0] += int(elem[2])
        mobiledict[key][1] += int(elem[3])
    else:
        mobiledict[key] = [int(elem[2]), int(elem[3])]
print(mobiledict)
